The lines by Ogden Nash--``If called by a panther, / Don't anther''--aptly kick off this story, narrated by a PI who maintains his comic-ironic tone even in the face of danger. Albert Samson has reluctantly decided to promote his services in TV ads that label him a ``go-for-it'' detective. Meanwhile Indianapolis newscasters scream about ``The Scum Front,'' a band of environmentalists holding the city hostage with bomb threats. On the trail of a woman who removes a bomb from its hiding place, Samson is also hired by the Scummies, and, aided by spunky artist Bobbie Lee risks life and license to help the police halt the terrorist campaign--if only the police will let him. Among the growing number of American regional mysteries, this is not a standout; otherwise well-crafted, it needs a clearer evocation of place. Lewin also wrote Late Payments. (June)